[xBhp Universal Thread]: Universal Thread - Braking

[Lucky Luke]

Originally Posted by aditaya.chopra

can anyone tell me the procedure to convert my front single disk to double disk of my r15 and where i can find its material

Hi.
Why would you do that? To look like you've got a bigger machine or what???
All what you would get is heavier "non-suspended" weight. This means that your front wheel will bounce more as the shock absorber in the fork will not be able to cope with such weight. You wil also apply more braking power than what the friction of the tire on the road can accept, and block your wheel!

The question you have to ask yourself is: why are some bikes fitted with double disc and some with single?

The answer is: weight* speed= kinetic energy, and dissipation of this energy when braking (which energy has converted into heat). Tire contact area with the road has to be considered too, as well as the tire's nature, etc....but that would make a too long discussion.

Your R15 is a mere 130 kg, plus gas and yourself. The speed is some 140kmh "practical" maximum. It is not difficult to stop it's little kinetic energy, hence little heat dissipation. Also, we are supposing that you are on the road, not racing. A single caliper can apply enough pressure on the disc and this single disc can easily dissipate the (rather small) heat caused by braking.

Now consider a >200kg, 250kmh capable 1,000cc. bike. The kinetic energy (Ec) needed to stop this mass (m) at that speed (v) is considerable: Ec= 1/2 m*v2 (not to be confounded with Einstein's E= m*c2 !!!). There is much heat to dissipate, and unless one has a very large disc (the limit being the wheel's diameter) the pressure to apply can be just too high for a single caliper, no matter how many pistons in it. In this case, a double disc makes sense. The additional "non-suspended" weight will be a lower fraction of the weight of the whole bike (+ gas and rider). Also the fat front tire with soft compound of this performance bike will accept much more friction with the road before blocking.

While commenting this, I also want to comment about someone's suggestion/ question earlier about fitting one more caliper on his disc. That would be, excuse me, another nonsense. All it would do (besides, as here-above, additional non-suspended weight) is to need less hydraulic pressure for the same braking power, while this pressure is simply depending on the effort aplied to the lever (and the ratio of surfaces in the hydraulic system). If his hand is not strong enough, just lengthen the lever (or do some exercise). Even in race/ emergency braking, two fingers is enough, so what...!!??.
The other thing this "twin caliper" would do is to double the pads area. DANGER: absolutely great way to jam the wheel!

Please guys: stop thinking about "improving" the braking of your bike by such and such "miracle" mod. One which is worth it, though, is to have a rear disc on thse bikes where cost was a prime consideration and are fitted with a (although sufficient most of the time) drum rear brake instead of a disc. Personally, I like the feeling and the endurance of front and rear disc brakes, but that is all. If your bike manufacturer (or his competitors) does not offer different system as option (for example FZ16= no rear disc, Dazzler= rear disc option), just trust them: they know their job pretty well!

[chiragwarm]

For the 1st time after 2 years and 8k KMS. I changed brake fluid to Castrol & rear brake has become pretty loose. Mech told me as the new oil flows, it will get tight.
Should I tighten my rear break as indicated in the manual or ride and wait for it to become tight ?

[antz.bin]

Originally Posted by chiragwarm

For the 1st time after 2 years and 8k KMS. I changed brake fluid to Castrol & rear brake has become pretty loose. Mech told me as the new oil flows, it will get tight.
Should I tighten my rear break as indicated in the manual or ride and wait for it to become tight ?

GS150R?
Rear Brake?
Fluid??

Please tighten it as mentioned in the manual.